Former top Khmer Rouge official Ieng Thirith has died, according to Cambodia's U.N.-backed war crimes tribunal.

Ieng Thirith died Saturday at the age of 83, said a statement by the Extraordinary Chamber in the Courts of Cambodia, or ECCC.

Known as the "first lady" of the Khmer Rouge, Ieng Thirith served as the minister of social action during the regime's bloody, four-year rule.

Her husband was former foreign secretary Ieng Sary, who died in 2013 at age 87, before the genocide case against him could reach a verdict.

Ieng Thirith was originally charged with genocide and crimes against humanity before being found mentally unfit for trial because of dementia and released. She remained under judicial supervision until her death.

The ECCC statement did not say how she died.

As many as two million Cambodians died from starvation, overwork and executions during the rule of the Khmer Rouge, which attempted to create an agrarian communist utopia.

Former head of state Khieu Samphan and chief ideologue Nuon Chea are currently on trial at the Phnom Penh court, facing charges for a wide array of crimes, including genocide.

The two have already received life sentences from the court for their roles in the mass emptying of Phnom Penh following the Khmer Rouge takeover. They have appealed that decision.

The trial has been split into two parts due to concerns about the slow pace of the proceedings and the advanced age of the defendants, who are both in their 80s.

Khieu Samphan and Nuon Chea are the most senior leaders to be convicted by the tribunal, which began operations in 2006 and has since experienced funding issues, corruption and other scandals.

In 2010, the tribunal convicted and sentenced to life in prison former Khmer Rouge prison chief Kaing Guek Eav, better known as "Duch," for his role in killing more than 14,000 while running the Tuol Sleng center in Phnom Penh.